Contribution to 1, say, left out connection with drug (6)
I believe the answer is:
inkpot
'connection with drug' is the definition.
I can't tell whether this defines the answer.
'contribution to 1 say left' is the wordplay.
'contribution' becomes 'nk' (I can't explain this - if you can you should believe this answer much more).
'to' says to put letters next to each other (I've seen this in other clues).
'n' becomes 'I' (Roman numeral).
'say' becomes 'top'.
'left' shows that the letters should be reversed in order.
'top' written backwards gives 'pot'.
'nk' after 'i' is 'ink'.
'ink'+'pot'='INKPOT'
'out' is the link.
Can you help me to learn more?
(Other definitions for inkpot that I've seen before include "Topper-up for old writer" , "Here perhaps blue fluid" , "that may assist writer" , "Vessel for writing fluid" , "Source for old writer" .)